This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-069230, filed Mar. 13, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a method of manufacturing a semiconductor device characterized by comprising a step of patterning a film such as an insulating film by using a masking material.
When a micro pattern is formed by a conventional method, an insulating film or a metal film is processed by using a patterned resist as a mask. The method of micro-processing the insulating film will be explained with reference to FIGS. 11 to 14.
First, as shown in FIG. 11, a first resist film 22 is formed on an insulating film 21 and subsequently a Spin-On-Glass (SOG) film 23 is formed on the first resist film 22. A second resist film 24 is coated on the SOG film 23, followed by being patterned.
Subsequently, as shown in FIG. 12, the SOG film 23 is removed until the surface of the first resist film 22 is exposed. As a result, the SOG film 23 is patterned. During this process, the resist film 24 is partly removed.
As a next step, as shown in FIG. 13, using the patterned SOG film 23 as a mask, the first resist film 22 is removed until the surface of the insulating film 21 is exposed. In this way, the first resist film 22 is patterned. In the patterning process, the second resist film 24 is also removed. After that, the patterned SOG film 23 is removed.
Subsequently, as shown in FIG. 14, using the patterned first resist film 22 as a mask, the insulating film 21 is removed by dry etching. As a result, a trench 25 is formed in the insulating film 21.
In the aforementioned conventional method, the trench 25, which must be finely processed, is formed by using the patterned first resist film 22 as a mask.
Since the micro-processing requires improvement in resolution, the thickness of the first resist film 22 serving as a mask has to be reduced. On the other hand, to form a fine trench 25 by dry etching using the first resist film 22 as a mask, the first resist film 22 serving as a mask must have a thickness sufficient to ensure an appropriate etching selective ratio.
Therefore, a micro-processing method is required for stably processing a film such as the insulating film while ensuring a sufficient lithographic margin and a sufficient film thickness of a masking material during dry etching.
The present invention was made to overcome the aforementioned problems. An object of the present invention is to provide a method of manufacturing a semiconductor device by micro-processing while ensuring a sufficient lithographic margin and a sufficient film thickness of a masking material during dry etching.
The present invention employs the following means to attain the aforementioned object.
The method of manufacturing a semiconductor device of the present invention comprises the steps of:
forming a first organic layer on an insulating film;
forming a second organic layer on the first organic layer;
patterning the second organic layer;
forming a silicon oxide film or a metal-containing inorganic film on an entire surface of the patterned second organic layer, thereby covering the second organic layer;
removing the silicon oxide film or the metal-containing inorganic film, the second organic layer, and the first organic layer, by dry etching, thereby patterning the first organic layer and the silicon oxide film or the metal-containing inorganic film;
removing the silicon oxide film or the metal containing inorganic film and the insulating film by using the patterned first organic layer as a mask, thereby exposing the surface of the patterned first organic layer and simultaneously forming a trench in the insulating film; and
removing the first organic layer.
Furthermore, another method of manufacturing a semiconductor device according to the present invention may further comprise a step of forming an anti-reflection film on the first organic layer after the first organic layer is formed. The anti-reflection film used herein is an organic anti-reflection film formed of flare, silk, polyimide, fluorocarbon, or tri-acetylene.
The first organic layer is formed of a resist film, a coating-type carbon film, a sputtering-type carbon film, or a low dielectric film.
It is desirable that the silicon oxide film should be one selected from the group consisting of an SOG film, coating-type organic silicon oxide film, coating type organic silicon film, or coating-type inorganic silicon film.
It is desirable that the metal-containing inorganic layer should contain a coating-type inorganic layer containing at least one metal selected from the group consisting of WO3, Al2O3, TiO2, and TiN.
The second organic layer is a negative resist film. Furthermore, the second organic layer is patterned by electron beam drawing. Moreover, the second organic layer is thinner than the first organic layer.
Another method of manufacturing a semiconductor device of the present invention may further comprise a step of irradiating the entire surface of the resulting structure with ultraviolet rays after the second organic layer is patterned.
As explained above, according to the present invention, it is possible to provide a method of manufacturing a semiconductor device by micro-processing while ensuring a sufficient lithographic margin and a film thickness of a mask material during dry etching.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.